The present invention relates to an apparatus and a method for treating and separating emulsified liquids. Thus, the invention relates to cleaning and separating of emulsified liquids, especially cooling/lubricating oil emulsions, degreasing water, oil-containing waste water, waste water from laundries, from food production, solvents and the like. The method involves vapor compression wherein emulsified liquids in a sump are heated to a temperature level just below the boiling point of the liquid to be distilled, and in which the vapors which are produced at a first side of a heat exchanger and in the sump are compressed in a compressor, whereby the temperature is increased, and which compressor leads the so-heated vapors into the second side of the heat exchanger in which they are cooled and condensed, and in which the heat released by the condensation is transferred to the emulsified liquid at the first side of the heat exchanger so that the liquid to be distilled is evaporated, and wherein the level for this temperature range is determined on the basis of the desired distillate. The separation of the specific substances and water or solvents is often required due to recycling of the water and/or for reducing the costs of transportation and destruction of waste water.
Industry uses various solvents, e.g., for degreasing and cleaning. In addition, the engineering industry uses cooling/lubrication oils mixed with water. These often enter into a heavy emulsification with the water, which means that the emulsified liquid is very difficult to separate. When the agent for degreasing, cleaning, cooling and lubricating has been used a number of times, it becomes saturated with dirt, heavy metals, moisture, and other impurities. Therefore, a concentration or a destruction of the agent in question is required.
Usually the concentration of solvents is performed by means of a simple boiling, followed by a subsequent cooling, typically by using water as cooling agent. This method is disadvantageous as it is energy consuming.
In recent years the concentration of cooling/lubricating oil emulsifications has been impeded because softeners are added to the cooling/lubricating agents, thus the oils emulsify heavily with water. Consequently, a subsequent concentration is very difficult.
Besides boiling, a chemical method for separating emulsified liquids is known. However, chemical separation is an expensive method requiring an exact adaption of a demulsifying agent, and usually it will only be economical at concentrations of polluting liquids in the main liquid lower than 1%.
Yet another method for concentration of solvents is known, viz. the so-called ultra filtration, in which the specific elements are separated by filtration. This process is also expensive, and moreover problems as to clogging of the specific filters arise, and consequently the method is subjected to uncertainty and requires a demand for frequent supervision.
U.S. Pat. No. 4,698,136 discloses a method corresponding to the above-described method wherein for continuous cleaning of water containing salt, hydrocarbons and Fe.sup.++, mechanical vapor compression is used. According to this patent, the liquid to be cleaned is initially subjected to a mechanical cleaning in the form of gravitation separation. This gravitational separation however, cannot separate stabilized emulsions. And if the liquid emerging from the mechanical cleaning step is a stabilized emulsion, the process described cannot provide an efficient cleaning and separation.
As mentioned above, the principle used is referred to as mechanical vapor compression, and it is disclosed in Danish Patent Nos. 68,529 and 78,060 filed by Mr. Rolf Andersen. It has been used for treating radioactive waste water, for producing drinking water out of sea water, as well as for concentrating brine, exclusively for use in very large complicated systems.
It is the object of the present invention to remedy the disadvantages associated with the known processes and to provide a method in which the separation is established by means of a boiling process and a subsequent cooling and in some cases by means of gravitational separation, and by subsequent cooling using a minimum of energy.